class Maybe{
  static of (value) {
    return new Maybe(value)
  }

  constructor(value) {
    this._value = value
  }

  map (fn) {
    return this.isNull()? Maybe.of(null):this.isUndefined()? Maybe.of(undefined):Maybe.of(fn(this._value))
  }

  isNull () {
    return this._value === null
  }
  isUndefined () {
    return this._value === undefined
  }
}

class Container{
  constructor (value) {
    this._value = value
  }

  static of (value) {
    return new Container(value)
  }

  map (fn) {
    return Container.of(fn(this._value))
  }
}

module.exports = {Maybe, Container}